Posted
by
Soulskillon Monday August 02, 2010 @05:17PM
from the flying-rice-burner dept.

fergus07 writes "Borne out of the same NASA research program that gave birth to MIT's D 'double bubble,' Boeing's Subsonic Ultra Green Aircraft Research (SUGAR) Volt concept is a twin-engine aircraft design notable for its trussed, elongated wings and electric battery gas turbine hybrid propulsion system — a system designed to reduce fuel burn by more than 70 percent and total energy use by 55 percent. The goal of the NASA supersonic research program is to find aircraft designs that will significantly reduce noise, nitrogen oxide emissions, fuel burn and air traffic congestion by the year 2035."

That's because most people have no idea how cool the now technology is. The Internet is absolutely amazing on pretty much every technological level, and yet to 95% of the world, its technology is indistinguishable from the magic of a radio.

I would gladly exchange all the cellphones in the world for being able to walk on the moon.

You know, I'm thinking that the ability for *anyone* to communicate instantly with *anyone else* in the world by voice or text (or for a few, video) with just a tiny box about the size and shape of a "communicator" from Star Trek from—get this—40 years ago, is probably better than sitting at home watching on TV a couple of other guys bounce around hitting golf balls on a cold, dead rock that offers us no immediate chance for advancement beyond the psychological thrill of saying "someone else oth

The ability of a private person to go to space is getting better. Not worse... In a manner of speaking.

The problem with the moon shot is that it was little more than a pissing contest with pork. Just like NASAs constellation, its not the path to the stars for joe anybody. So unless all you want to do is watch a special few do "future" things, it was and still is a bad metric to use. Just like the stupid phrase.."if they can put a man on the moon....."

maybe our ability to walk on the moon depends on our ability to understand that if we keep fucking with the earth the earth will one day say fuck us all. after we are all gone, it can happily continue and look beautiful again in a few million years. but we're a pretty nasty virus and we'll respawn pretty quick. we'll be back on earth some day...

We're not a virus. We're the most interesting thing that has yet happened on Earth, perhaps in our whole galaxy. Just because there are minor teething problems coming from our heritage, doesn't mean that we aren't trying and don't deserve to exist.

maybe our ability to walk on the moon depends on our ability to understand that if we keep fucking with the earth the earth will one day say fuck us all.

If we go by the Gaia hypothesis, as you seem to be doing, then we're the closest thing the Earth has for brains, the Internet is the nervous system, and the Moon landings were the first few tentative roots growing onto a bare rock. All of which would make us fucking with the Earth masturbation, and Earth saying "fuck you all" to us incestercubation. Gaia i

assuming we don't destroy ourselves in the next 2035 years, don't you think the tech of 4045 will be cooler than the tech of 2035?

Not necessarily. I know of at least one ancient technology [google.com] that was still cooler than what they could do 1700 years later.

When they wanted to build a bridge over the Gardon river in France in 1740 they followed the same design that the Romans had built [wikipedia.org]. The new bridge was an expansion of the lowest line of arches of the ancient aqueduct.

This story is somewhat of a dupe (too lazy to look up the original, though it was less than a year ago), and this point was brought up then too.

When you're talking about advanced aircraft, the "25 years effect" is not the same as it is for overhyped things like fusion power; here, there's actually a reason. Aircraft take a loooooooong time to go from concept to flight: recall that Airbus starting thinking about the A380 in 1988, made it an official project in 1994, and it started commercial flight in 2007. And that's for a conservative design that was just building on existing principles. For a radical, untested design it would be considerably longer. Looking at it from that point of view, 2035 is actually a very reasonable target.

The first car was unprofitable. The first version of the Internet was unprofitable. The first everything is generally unprofitable. Reduce fuel costs by about 50%, reduce sonic boom to match federal guidelines for land crossing, and you have a profitable supersonic airplane.

Don't forget, the Concord was '70s technology. Even 90s technology could have done better.

The thing wasn't cheap, but there was no other option on Earth. There simply wasn't (and isn't) a way to get between NY and London faster. You can't buy a supersonic jet, and the military won't let you borrow one.

There are one or two supersonic business jets, but they're so expensive (about as expensive as buying an ex-mil supersonic jet and getting it refurbished to the required standard) that "you can't buy one" essentially still applies.

You can buy MiG and Sukhoi fighters. They've been demilitarized, of course, but they're still capable of supersonic flight, and can be flown in the US, provided you have the proper licenses and ratings. There's a guy on the East Coast that owns several MiGs, IIRC.

No, not useful nor economic for SST, but why wouldn't you get them over the ocean? That's where you can pass Mach 1. Stay on an IFR flight plan, keep the ADIZ in mind, and make damned sure you don't drift inside of it during supersonic flight without notifying ATC, lest you find a fighter of somewhat different make behind you and a sudden need to test your ejection seat.

In the old days transatlantic flights involved a stopover in the Azores isles, about halfway between Europe and N. America. If you really can afford to have MIG 23 in the garage you'll probably get to places quicker stopping over for fuel than waiting for a Boeing 747.

I'm well aware of how much fuel most jets use when flying supersonic. Only the Concorde and a few recent fighters do well at speeds above Mach 1; even the B-1B uses supersonic flight for only quick runs in and out because it sucks fuel.

The question that I was answering was whether "slightly used Russian ex-military aircraft" were available, not whether it was a practical purchase. Of course it's not. Hell, flying oneself around is not usually a practical option unless you're one of the rare ones who can

You've reminded me of something about Concorde - told to me in a pub conversation, so likely rubbish - and I've since tried to get some proof for it but failed however maybe it is of interest:Apparently the Concorde could cross the Atlantic faster than the much faster attack fighters because it did not need to do in air refuelling. i.e. there is no point going at mach 5 if you need to keep slow ingconstantly to in-air refuel. This meant that it actually scared quite a few military planners because under sta

Currently, federal guidelines are mutually exclusive to any aircraft which breaks the sound barrier. This is something current aerospace biggies have repeatedly pointed out. We already have designs which can satisfy all reasonable super sonic noise demands. Meaning, you *might* occasionally hear a very distant boom but you would never have the associated window shaking.

Besides, most (all?) studies indicate the vast majority of complaints associated with sonic booms never actually existed. More often than no

If true then the lobbyists should have no problems changing the regulations.

They were actually well on their way of addressing it when super sonic transports were all but canceled because of fuel economics. So until economics make it politically viable to address it again, I don't expect it will change.

So the Concorde was uneconomical when fuel was much cheaper, so all we have to do is make fuel half a cheap as it is now, even though it's only going to get more expensive in the future? American guidelines have nothing to do with it, the point of supersonic travel is transoceanic.

Flying wings have many excellent characteristics but mass passenger transport isn't one of them.

In order to accommodate large passenger loads the flying wing shape becomes abused which leaves behind many of the characteristics which make the flying wing attractive in the first place. Once you modify the flying wing shape to accommodate large passenger loads, you more or less have a shape which is portrayed in the designs presented. And once you accommodate construction/materials issues, it almost exactly looks like the designs presented.

In other words, I'm not really seeing a problem. But, as you mention, hopefully some designers won't be silent.

Another problem is turning. Right now sitting close to the center of gravity, when a plane turns you travel a few feet up or down. If you were sitting 20 or 30 feet from the center of gravity, you would travel much further. Most people would feel very uncomfortable doing this. Pilots would have to perform only flat turns, using the rudders. I don't know how practical this would be.

Another problem is turning. Right now sitting close to the center of gravity, when a plane turns you travel a few feet up or down. If you were sitting 20 or 30 feet from the center of gravity, you would travel much further.

I'd pay extra for a seat further out. Assuming I don't have the flu or something, that would be fun.

Depends on the turn. Like I mentioned above, it is possible to combine pitch, roll, and yaw into a coordinated turn, where your net apparent "gravity" (centripetal acceleration, however you like to think about it) is straight down through the floor.

I am no aerospace engineer, about as far from it as you can get, but I would think that wing = drag.

Congrats on accidentally making the wrongest statement ever on/. On an airplane, wing = lift. And since the purpose of the airplane is to go up, lift = good. The part the people sit in, that uniform shaped tube body, equals drag. An airplane shaped like a big wing could thus lift the most and drag the least. (see: Northrop YB-49)

A tube body can actually produce some lift if it's shaped correctly but it's very expensive to manufacture and tricky to design (see: Super Constellation).

Well, on the free body diagrams I drew in my flight dynamics classes, Jeng is more right than you are.

Induced drag is the component of the lift vector that opposes the thrust vector. Induced drag is a component of the net drag on the airframe. It's not generally useful to think of induced drag as a part of the lift force.

You can draw your vectors however you want, but nitpicking other peoples' coordinate systems doesn't make you look like you know what you're talking about.

You realize that "just a few feet of water" is more like 22 feet (7.5m) of water.At 35000 feet (10.5 km) cruising altitude for non-super sonic airplanes, air density is 25% of see level air density. 1 atmosphere is about the pressure of 10m of water column.Everest is "just" 8848 m, and yet very few can breathe easily without several days acclimatization.See altitude sickness. Even oxygen masks may not be enough at very low pressures.

While I don't refute your point, Pla123, I feel I should point out that passenger aircraft are not pressurized to sea level pressure. I believe--and no, it isn't fact, but I bet it's pretty close--that airliners are pressurized to ~7000 feet above sea level. What is that, like, 800mb? Anyway, there it is.

Although to be honest, altitudes around 7,000' aren't that bad. I've been in aircraft with the doors open above 15,000' without noticing anything except my ears popping. I'm not sure I could comfortably jog at that altitude but then again that's not something you typically do on an airplane.

I've spent countless hours on military cargo aircraft (that were sealed like a screen door), flying at cruising altitude, without

Although to be honest, altitudes around 7,000' aren't that bad. I've been in aircraft with the doors open above 15,000' without noticing anything except my ears popping. I'm not sure I could comfortably jog at that altitude but then again that's not something you typically do on an airplane.

I've spent countless hours on military cargo aircraft (that were sealed like a screen door), flying at cruising altitude, without noticing anything. The only weird part is walking around a compartment that's twice as big as my house and few miles over the atlantic.

-b

That's coz you're a healthy young chap.

Last flight I was on, I was sitting next to some old ladies, and several of them mentioned that they needed oxygen on longer trips after we saw an anaemic young girl faint. Her lips were blue!

Low partial pressures of oxygen are hell on people who's lungs are already borderline capable of keeping them alive at sea level.

it's not a huge pressure differential. Less than a few feet of water in reality.

Between 8 and 9 psi, typically. Almost 20 feet of water. It's not such a big deal when the structure is circular since the stress is all tension. Much tougher when you try to build large, flat surfaces.

To fit passengers comfortable into the wing, it needs to be a goddamn big wing. A wing that big could only be used on the most mass of the mass transit routes to be economical, would be expensive to develop, and would require airports to be rebuilt to accommodate them at the terminals (real deal-killer). Like any cool new thing, it's legacy compatibility that scuppers it.

Another problem with a flying wing passenger aircraft is the fact that there won't be many, if any, window seats. Okay, minor problem? What about the forces that would act on people towards the wingtips when banking? A relatively minor turn that would barely be noticed in a tubular airframe would be magnified into a fifteen foot drop or rise towards the edges. Now imagine trying to land in turbulent, stormy weather, and being really far from the center axis of the aircraft. Whatever money would be saved by the efficient wing design would be eaten up by barf bags and steam cleanings of the cabin after every flight.

A relatively minor turn that would barely be noticed in a tubular airframe would be magnified into a fifteen foot drop or rise towards the edges.

Why do you think it'd feel like a 15 foot drop or rise? I doubt it would, if the turn were done smoothly. From what I'm reading, roll control (the control of rotation of the axis along the direction of travel) is not a serious issue with flying wings. That seems to indicate to me that the issue of storms and such (most which wouldn't generate a significant rolling motion in the vehicle) is a bit exaggerated.

Why do you think it'd feel like a 15 foot drop or rise? I doubt it would, if the turn were done smoothly. From what I'm reading, roll control (the control of rotation of the axis along the direction of travel) is not a serious issue with flying wings. That seems to indicate to me that the issue of storms and such (most which wouldn't generate a significant rolling motion in the vehicle) is a bit exaggerated.

I didn't say it'd feel like, I said it would be. Obviously I have no way of knowing how many flights you've been on, but, next time you're on one, look out the window from right after takeoff until about fifteen minutes into the flight. Do the same thing at the end of the flight. Watch the wingtips in comparison to level reference, the ground or horizon or clouds. Note how the plane has to bank rather frequently after takeoff and before landing. Note how the wingtips of your plane go up and down several fee

For the pictures, it looks like the subsonic airplane is equipped with turboprop engines - or are these propfans ? If so, our next generations airliners might very well be equipped with propellers again: Airbus is also considering propfans [espacenet.com].

I'm very surprised that a turbine driving an generator, powering an electric motor driving a fan is more efficient (including the extra weight) than a turbine directly driving the fan. Airliners usually cruise at altitudes where the engines are run at near max-efficiency power (at that altitude).

Maybe because the bits of the journey that aren't at cruising altitude use up a disproportionate amount of fuel, and the inherent qualities of electric propulsion means it might be better suited to the job?

Jet engines are already de-facto propeller engines. If you call it a "Fan" it doesn't sound as scary as "Propeller." In a high bypass turbofan engine such as those found in most modern aircraft, most of the thrust is produced by the fan part of the turbofan. For example, the CF-34 [wikipedia.org] jet engine has a bypass ratio of 80% or better. This means 80% of the thrust is produced by spinning a fan. Newer designs like the Rolls-Royce Trent 800 [wikipedia.org] get 84% thrust from the bypass fan. Basically, anything that can create radial motion can be use to turn that fan. Electric, steam, compressed air,.... {insert physics here}.

The bypass ratio refers to the mass of air moved around the core to the mass moved through the core, not the ratio of thrust. For any given mass of air being put through the core, it will produce more thrust than the same ratio outside the core because it gets hotter/faster.

I'm not really able to challenge your statement. I will, however, cite that years ago I read one the pilot manuals for the Bombardier CL-65 (aka Canadair Regional Jet) which uses CF-34 engines. The manual did indicate that 80% of the thrust came from bypass air. Manuals prepared by the manufacturer do seem reasonably authoritative. If that figure is wrong, I'm merely repeating a wrong.

Jet engines are, by definition, not fans. They produce thrust by the acceleration of a jet of combustion products exiting the rear of the engine through a nozzle. Rockets are jet engines; but the term jet engine usually implies air-breathing and rockets are assumed to carry their own oxidizer. Propellers/fans produce thrust pushing air back by rotation of the fan blades/fan wheels/propellers.
Fans can be propellers or otherwise. When talking about aircraft it's usually meant that a prop is un-ducted bu

I had 'jet fuel' as on my list of things that wouldn't ever likely get replaced with electric storage, and now this reduces the list a bit. Can we just start putting up some modern nuclear reactors and get out of the Middle East then? We've got plenty of sources here for real oil needs.

Close. The Fischer-Tropsch process uses hydrogen and carbon monoxide (CO) and the catalyst used in reactors can be from cobalt, iron, ruthenium and nickel. Synthesis gas or water gas is another source of H2 and CO. It is derived by passing steam over a bed of red hot hydrocarbon fuel such as coke. The result is a CO and hydrogen mix. Biomass can also be used to produce CO as well (and possibly syn-gas.) So in theory we can produce carbon neutral hydrocarbon fuels from biomass and hydrogen from water. Plus y

Brilliant! Absolutely brilliant! The folks in the US got their drawers in a knot, when the Concorde wanted to fly over, "because it was too loud." What do you think they will say, when they have a Hiroshima or Nagasaki flying over their heads?

Everyone can stomach a nuclear submarine or aircraft carrier, because, well, they aren't going to dock in their backyard. (Apologies to the folks in Groton, Norfolk, and San Diego). If an accident happens, only a few whales, and other sea critters will be harmed.

Brilliant! Absolutely brilliant! The folks in the US got their drawers in a knot, when the Concorde wanted to fly over, "because it was too loud." What do you think they will say, when they have a Hiroshima or Nagasaki flying over their heads?

Stop getting your panties all bunched up... You do realize that the comment you're replying to talked about "electric storage"? Noone is gung-ho about flying nuclear ('cept maybe Emmet "Doc" Brown)... but if you can generate electrical via Nuclear (and Wind/Solar) and

These things are still going to be carrying oil of some description rather than charged up batteries for most of their energy requirements. The additional weight of batteries is not going to make sense for an aircraft.

I'm not sure trains are a good model either; Diesel-electric trains are effective because the torque you need for starting & driving a train doesn't easily come from a diesel motor without lots of gearing and clutches that are complex, inefficient and potentially unreliable.

Electric motors can give you all the torque you want from a standing start and so they make it easier to use diesels, avoiding the need to electrify your rail network (partly the reason Britain went with Diesel-electric trains in the

Yes, once they get to crusing, but they have to get that far first. This also uses exposed props which to meet noise regulations are going to be running at a speed that without complex gearing would not make a jet very fuel efficient.

The picture seems to show scimitar prop blades, which are much more efficient and produce less blade noise. I can also see where the props could have a battery-assisted power boost during take-off and climb to reduce overall engine noise while maintaining performance.

I can imagine this getting a negative PR image, though, because the general populace will see it as going backward. I already hear enough people complaining about the return to space capsules instead of developing another winged spacecraft.

I can see where they could use stored electricity to shut engines off when landing to reduce noise, charge at the gate, and take off without engines as well.

That alone wouldn't affect efficiency necessarily, but would probably allow the use of louder engine types that might be able to reduce efficiency, and it would reduce the opposition to airports allowing them to be placed in better locations.

So what is the advantage of a hybrid plane? Unless there has been some sort of breakthrough in battery technology, the extra weight your carrying around is going to use more energy. A discharged battery is not substantially lighter than a full one, whereas with liquid fuel tanks weigh a lot less when (nearly ) empty..

I guess you can get a bit of energy back on landing with regenerative braking, but not enough to make up for the extra weight.

Battery weight could certainly be an issue. I suppose though that you could start off fully charged on the ground and use that for a boost to get you aloft.

Something that comes to mind is that, AFAIK, in a hybrid system you try to keep the combustion engine turning at it's ideal RPM regardless of load. Assuming that's the case, would there be periods where you might have extra capacity beyond what's needed for the electric motors and other electrical systems? Let's assume there is - what do you do with i

"The goal of the NASA supersonic research program is to find aircraft designs that will significantly reduce noise, nitrogen oxide emissions, fuel burn and air traffic congestion by the year 2035."

Reduce air traffic congestion?

What? Are they solar powered and only fly on the sunny side o' Earth?

The article mentioned both air-speed decreases and fueling/loading times lowered. Both of those mean more airtime, which in turn means more planes in the air at any given time. How does that equate to "reduced air t

NASA is taking an integrated approach to the problem. By carefully scheduling arrivals and departures to minimize loitering, you reduce fuel burn. You have to be clever in how you control aircraft that fly closer to one another than they're allowed to today. It's a complex problem.

For those not up to speed on jet engine technology, modern turbofans are essentially ducted propellers [wikipedia.org]. The engine itself occupies a small section in the center. It burns fuel and throws the air it consumes out the back at a higher speed. This generates about 20% of the total thrust. The rest of the energy goes into spinning the bypass fan blades. Just like a propeller, they grab large chunks of air which never goes through the combustion chamber, and push it out the back at higher speed to generate about 80% of the thrust.

In current engine designs, the blades of the two are locked together (although some of the compressor blades inside the engine may rotate at a different speed). For the bypass fan blades to be spinning, the engine must also be on and spinning. The idea behind this hybrid is to decouple them so they can operate independently of each other. The bypass fan would be spun using an electric motor. I don't know the numbers involved, but theoretically that would mean you could always run the jet engine at its most efficient RPM to generate electricity, and even turn it off if there's little thrust required and the batteries have enough juice to run the bypass fan (e.g. descent).

Do the math:
It is far faster, more energy efficient and easy on the environment, to fly out of the atmosphere in a suborbital trajectory, reentering near your destination.
Oh, but we have to wait for NASA to develop that and they are mothballing the shuttle program so it must be a non-starter.
Right?

LH2 tanks require more insulation (meaning more weight). The planes can only carry so much fuel by volume. The maximum fuel capacity for a 737-NG is 26,000 liters. The density of Jet A at 15C is about 800g/L. The density of liquid hydrogen is 71g/L at 20K. At these densities, you get masses of about 21,000kg of Jet A and 1900kg of LH2. The specific energy of Jet A is about 43MJ/kg, and 143MJ/kg for LH2. At those levels, you get total stored energy of about 1.1 million MJ for Jet A, and only 270,000 M

They tried building a hydrogen powered spy plane back in the 70s or something. LH2 is kind of a nightmare to deal with compared to jet fuel. For one thing, its a cryogenic. The US Air Force decided that playing with LH2 was a) too dangerous and b) too much of a logistics headache. And even with LH2, your energy density is still significantly lower than jet fuel. They had a nightmare trying to get the range required on that spy plane. Wiki-link for you: http://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan. If